1. Field of the Invention
The present invention relates to a resin production apparatus and a resin production method, for producing a synthetic resin such as an acryl oligomer which is used in tackifiers for adhesive tapes.
2. Description of Related Art
When small pieces of a synthetic resin are produced by polymerizing ingredients, the ingredients are usually molten and kneaded while being polymerized to prepare a desirable synthetic resin. The synthetic resin is then cooled, solidified, and pulverized. For example, Japanese Unexamined Patent Publication No. 192604/2001 (Tokukai 2001-192604) discloses a method employing a screw type heating and cooling apparatus or a heat-type agitation and thermal treatment machine as a reactor vessel. In this method, ingredients are heated, molten, and mixed under reduced pressure. Then, the molten product is mixed and dispersed by using a melting-mixing-dispersing machine such as a bi-axial extruder. The resulting product is cooled by a cooling belt or the like, and is coarsely ground, pulverized, and sorted. Further, in the method disclosed in Tokukaihei 5-112654 and Tokukaihei 5-247225, ingredients are supplied in a reactor vessel having a rotating arm. The rotating arm repetitively applies shearing force to the ingredients. This way, a series of processes from preparation of a synthetic resin to pulverization of the product into small pieces are carried out within the reactor vessel. Further, Tokukai 2003-137929 discloses the following method. Namely, ingredients and a particulate polymerization catalyst are supplied in a reactor vessel and are polymerized. Then, the product is placed in a deactivation cleaning tank, and unreacted ingredients are separated. After that, the product is subjected to processes such as drying and sorting using devices for performing these processes.
In the above mentioned traditional production methods, the reactor vessel is cleaned typically by supplying therein a solvent to dissolve and remove residual synthetic resin in the reactor vessel. However, in production of a thermoplastic synthetic resin which solidifies at room temperature, the synthetic resin remaining after the synthetic resin is taken out from the reactor vessel solidifies and clogs parts of the reactor vessel. This necessitates removal of residual synthetic resin in the reactor vessel every time the reaction is carried out. That is, a solvent needs to be supplied in the reactor vessel to dissolve the synthetic resin, before ingredients are supplied to the reactor vessel. The time required for this cleaning process undermines the productivity. Further, increases in the amount of the solvent used and the number of times the solvent is used cause increases in the cost and burden. Further, using a large amount of organic solvent raises the risk that the organic solvent contaminates an oligomer produced without using a solvent. This leads to quality deterioration such as an increase in the amount of VOC (Volatile Organic Compounds).
The present invention is made in view of the above problems, and it is an object of the present invention to provide a resin production apparatus and a resin production method, which requires a less time and burden for removing solidified synthetic resin remaining in the reactor vessel.